He S F, Wei J Y, Eyzaguirre C
Department of Physiology, University of Utah School of Medicine, Salt Lake City 84108.
Brain Res. 1991 Aug 16;556(2):333-8. doi: 10.1016/0006-8993(91)90326-q.
Clusters of glomus cells, isolated from rat carotid bodies, were cultured for up to 2 weeks. Afterwards, we simultaneously measured the intracellular pH (pHi) and membrane potentials (Em) of single cells with pH-sensitive and KCl-filled microelectrodes. In 89 control cells (bathed in saline equilibrated with 50% O2 in N2) pHi was 6.87 +/- 0.014 (SE) and Em -36.3 +/- 0.45 mV. In 42 cells, switching to air (about 20% O2) lowered pHi in 60% of them by as much as 0.14 unit (mean decrease, 0.05). In the remaining cells, pHi increased by as much as 0.18 unit (mean increase, 0.06). Application of 2.5% CO2 in 50% O2 (balance N2) reduced the pHi in 90% of 47 cells by as much as 0.44 unit (mean decrease, 0.14). pHi increased to a maximum of 0.05 unit (mean increase, 0.04) in the others. Either stimulus depolarized or hyperpolarized glomus cells (-5 to 8 mV) in approximately equal proportions. There was a significant and positive correlation between delta Em and delta pHi. This observation confirms the idea that the Em of glomus cell is H(+)-dependent. Results do not agree with the acidic hypothesis for chemoreception.
